1. Field of the Invention
The present invention relates to a terminal structure of a switch to be applied to a molded case circuit breaker, an electromagnetic contactor etc.
2. Description of the Related Art
The assembled structure of a conventional switch (for three-phase) which is applied to the aforesaid molded case circuit breaker is shown in FIG. 4. In the figure, a reference numeral 1 denotes a casing (resin casing) of three-divided structure formed by combining an upper cover 2, an intermediate cover 3 and a lower cover 4 in a fitting manner. A reference numeral 5 denotes a fixed contact shoe incorporated in the breaker portion of the casing 1, 6 a movablecontact shoe, 7 an arc-extinguishing plate, 8 a switching mechanism, 9 an operation handle and 10 an over current tripping device. A terminal portion 11 on power supply side and a terminal portion 12 on load side are formed at the front end and the rear end of the casing 1, respectively. The terminal portions 11 and 12 are provided with terminal conductors 13 and 14 drawn from the inner portion of the casing at every phase and also provided with terminal screws 15 engaged with the terminal conductors 13 and 14, respectively. Each of the terminal portions is partitioned at every phase by partition walls formed at the casing 1. Each of the terminal conductors 14 of load side is integrated with the fixed contact shoe and fixedly held at the intermediate cover 3 in a bent configuration of S-shape as shown in FIGS. 2A and 2B. In FIGS. 2A and 2B, a reference numeral 14a denotes a fixed contact, 14b an arc horn and 14c a wire connection portion drawn to the terminal portion 12.
The conventional structure of the upper cover 2 of the aforesaid cover 1 and the intermediate casing 3 which supports the terminal conductors 14 of load side are shown in FIGS. 5A and 5B. That is, the intermediate cover 3 is provided with partition walls 3a which elect upward so as to surround the wire connection portions 14c of the terminal conductors 14 of the respective phases drawn to the terminal portion and the terminal screws 15 (see FIG. 4). The terminal portion of the power supply side is configured in the same manner.
The intermediate cover 3 is also provided with terminal fixing grooves 3b which are formed at the right and left walls of the drawing path of each of the terminal conductors 14 of load side so as to extend along the drawing path, respectively. Each of the terminal conductors 14 is fixed to the intermediate cover in a manner that a lug portion extended from the left and right side edges of the terminal conductor 14 (the width of the conductor of the lug portion is W) is pressed into the corresponding terminal fixing grooves 3b from the forward direction and fixed and held at the assembling position. In the example shown in the drawings, the groove width of the terminal fixing groove 3b corresponds to the plate thickness T of the terminal conductor 14 shown in FIG. 2A, and the length of the terminal fixing groove is set so as to coincide with the length R of the lug portion shown in FIG. 2B.
The upper cover 2 is fitted and coupled on the intermediate cover 3 as shown in the drawings in a manner that, at this position, the side walls 2a of the upper cover 2 are overlapped on the outsides of the partition walls 3a elected from the left and right ends of the intermediate cover 3, respectively.
In a switch such as a circuit breaker or the like, it has been intended to increase the capacity while using the casing of the same frame size in order to miniaturize the size of the outer configuration, unify the type and reduce the managing processes of the designing and manufacturing procedures thereof. In this point of view, the conventional structure of the aforesaid terminal portion remains the following problems.
(1) According to the conventional switch, there has such a structure that the partition walls 3a elected upward from the intermediate cover 3 are respectively formed so as to surround the corresponding terminal conductors 14 drawn to the terminal portion for the respective phases and the upper cover 2 is fitted to the partition walls 3a from the outside. Accordingly, a space for inserting the wires into the terminal portion from the outside is limited by the partition walls. That is, the thickness of the side walls 2a and the partition walls 3a is required to be larger to some extent in order to secure the mechanical strength of the upper cover 2 and the intermediate cover 3. However, in a case of setting the thickness of the side walls 2a and the partition walls 3a to predetermined values, respectively, so as to make the size of the entire outer configuration of the casing within a predetermined value, the width V.sub.2 of a space for inserting a wire therein is inevitably restricted and becomes narrow.
Thus, when the casing having the conventional structure is still used, in a case where the casing for a switch with a smaller current capacity is also used as the casing for a switch with a larger current capacity, there arises a problem in use that a thick wire can not be inserted and connected from the outside.
(2) Further, although it is necessary to make the plate thickness of the terminal conductor larger in a switch specified to have a large current capacity, the terminal fixing grooves 3b of the intermediate cover 3 for fixing the terminal conductor 14 are arranged to have the same groove width along the entire length thereof in .he conventional casing. Accordingly, when the terminal conductor has a thickness larger than the groove width, the terminal conductor can not be pressed into and fixed to the terminal fixing groove 3b unless the terminal conductor is subjected to such a processing that the left and right side edges thereof are made flat, for example.